Golf club shaft formed of tubular bodies different in flexibility

ABSTRACT

A golf club shaft is formed of an upper tubular body and a lower tubular body, which are different in flexibility from each other and are coaxially coupled by a connection rod in conjunction with a washer.

FIELD OF THE INVENTION

[0001] The present invention relates generally to a golf club, and more particularly to a golf club shaft which is formed of a plurality of tubular bodies different in flexibility from one another.

BACKGROUND OF THE INVENTION

[0002] In general, a golfer purchases a golf club on the basis of the golf club flexibility that is most suitable to the golfer. The conventional golf club shaft is generally made of a flexible and lightweight fiber composite material. Such a golf club shaft has a greater ball-carrying capability. For a professional golfer or an ordinary golfer with strong arms, a metal golf club shaft is preferred. In addition to the metal golf club shaft, a golf club shaft made of a rigid material is also preferred. The rigid golf club shaft is more precise in terms of the ball striking point. The rigid golf club shaft has a better ball controllability at the expense of the ball-carrying distance. On the contrary, the flexible club shaft has a better ball-carrying distance at the expense of ball-striking precision.

[0003] The U.S. Pat. No. 5,735,752 discloses a golf club shaft having an insert. The insert comprises a spiral midsegment and two couplers extending respectively from two ends of the midsegment for coupling a shaft or head. The insert serves to adjust the flex point of the shaft. In addition, the insert controls the center of gravity of the shaft and reduces the impact at the expense of the ball-carrying capability and the ball controllability.

SUMMARY OF THE INVENTION

[0004] The primary objective of the present invention is to provide a golf club shaft which is formed of tubular bodies different in flexibility. The golf club shaft is characterized by a stable ball-striking point and a greater ball-carrying distance.

[0005] The golf club shaft of the present invention is formed of an upper tubular body and a lower tubular body which is coaxially coupled with the upper tubular body. The upper and the lower tubular bodies are different in flexibility from each other. The tubular body of a greater flexibility is responsible for improvement on the ball-carrying distance of the golf club shaft. The tubular body of a smaller flexibility accounts for the stable ball-striking point of the golf club shaft. The two tubular bodies are coupled by a connection rod, with both ends of the connection rod being inserted into the tubular bodies. A protective washer is disposed between the two tubular bodies.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 shows a plan view of a first preferred embodiment of the present invention.

[0007]FIG. 2 shows an enlarged sectional view of a portion of the circle “A” as shown in FIG. 1.

[0008]FIG. 3 shows an exploded view of the circle “A” portion as shown in FIG. 1.

[0009]FIG. 4 shows a schematic view of a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0010] As shown in FIGS. 1-3, a golf club shaft 10 embodied in the present invention comprises an upper tubular body 20, a washer 30, a lower tubular body 40, and a connection rod 50.

[0011] The upper tubular body 20 is of a tapered construction and is made of a carbon fiber material and a reinforcing metal filament.

[0012] The washer 30 is made of aluminium, tough metal, or engineering plastic material. The washer 30 has an outer diameter which is corresponding to the outer diameter of the tip or the upper tubular body 20. The washer 30 is pressed against the surface of the top of the upper tubular body 20.

[0013] The lower tubular body 40 is of a tapered construction and has a length and an outer diameter, which are corresponding to about one seventh of the dimension of the tip of the conventional golf club shaft. The lower tubular body 40 is made of a carbon fiber material and is greater in rigidity than the upper tubular body 20. The outer diameter of the large end of the lower tubular body 40 is corresponding to the outer diameter of the washer 30. The large end of the lower tubular body 40 is pressed against by the washer 30. The lower tubular body 40 is coaxial with the upper tubular body 20.

[0014] The connection rod 50 is used to couple the two tubular bodies 20 and 40 and is made of a resilient steel or other metal of a predetermined flexibility. The length of the connection rod 50 is about 4 cm. The connection rod 50 has an outer diameter corresponding to the hole diameter of the middle hole 22 of the upper tubular body 20 and the hole diameter of the middle hole 42 of the lower tubular body 40. The connection rod 50 is concealed in the shaft such that the connection rod 50 is located in the center of the washer 30, and that both ends of the connection rod 50 are inserted respectively into the middle hole 22 of the upper tubular body 20 and the middle hole 42 of the lower tubular body 40. The coupling of the tubular bodies 20 and 40 is reinforced by an adhesive. The connection rod 50 is provided in the periphery thereof with a knurled portion 52, in which the adhesive is held. The knurled portion 52 serves to provide additional friction. The connection rod 50 is further provided in one side thereof with a trench 54 extending along the longitudinal direction of the connection rod 50. The trench 54 serves to allow the escape of air contained in a head which is connected with the connection rod 50.

[0015] In light of the upper tubular body 20 being greater in rigidity, the shaft 10 is relatively stable at the time when the head hits a ball. As a result, the ball-hitting point of the head is not excessively deviated. In view of the lower tubular body 40 being greater in elasticity, the shaft has a greater ball-carrying capability. In addition, the metal connection rod 50 lowers the center of gravity of the shaft 10 of the present invention, thereby resulting in enhancement of the shaft-swinging inertia. As a result, the shaft 10 of the present invention has a greater ball-carrying capability.

[0016] The washer 30 also prevents the direct contact between the two tubular bodies 20 and 40. As a result, the crack of the tubular bodies 20 and 40 is averted. The contact surfaces of the washer 30 and the tubular bodies 20 and 40 are coated with an adhesive.

[0017] The length ratio of the upper tubular body 20 and the lower tubular body 40 is about 6:1, which is not exclusive. The coupling point of the tubular bodies 20 and 40 is preferably located in the lower portion of the shaft.

[0018] As shown in FIG. 4, a shaft 60 of the second preferred embodiment of the present invention comprises an upper tubular body 61, a lower tubular body 62, a washer 63 held between the two tubular bodies 61 and 62, and a connection rod 64 coupling the two tubular bodies 61 and 62. The upper tubular body 61 is made of a carbon fiber material and is thus greater in flexibility than the lower tubular body 62 which is made of the carbon fiber material and a metal material in the form of filaments. In addition to the carbon fiber material, other fiber-reinforced composite materials may be used. 

What is claimed is:
 1. A golf club shaft comprising: an upper tubular body of a tapered construction; a washer in contact with a top of said upper tubular body, said washer having an outer diameter equal to an outer diameter of said tip of said upper tubular body; a lower tubular body of a tapered construction and having a large and outer diameter equal to said outer diameter of said washer, said lower tubular body being smaller in length than said upper tubular body and being different in flexibility from said upper tubular body, said lower tubular body further being coaxially coupled with said upper tubular body such that said large end of said lower tubular body is in contact with said washer; and a connection rod coupling said upper tubular body and said lower tubular body such that said connection rod is put through a center of said washer, and that two ends of said connection rod are respectively inserted into said upper tubular body and said lower tubular body.
 2. The golf club shaft as defined in claim 1, wherein said upper tubular body is made of a carbon fiber material and is reinforced by filaments of a metal; wherein said lower tubular body is made of the carbon fiber material and is greater in flexibility than said upper tubular body.
 3. The golf club shaft as defined in claim 1, wherein said upper tubular body is made of a carbon fiber material; wherein said lower tubular body is made of the carbon fiber material and is reinforced by filaments of a metal, said lower tubular body being smaller in flexibility than said upper tubular body.
 4. The golf club shaft as defined in claim 1, wherein said washer is made of aluminium.
 5. The golf club shaft as defined in claim 1, wherein said connection rod is made of a resilient steel.
 6. The golf club shaft as defined in claim 1, wherein said connection rod is provided in periphery with a knurled portion and is fastened at both ends thereof with said upper tubular body and said lower tubular body by an adhesive.
 7. The golf club shaft as defined in claim 1, wherein said connection rod is provided with a trench extending along the direction of a longitudinal axis of said connection rod. 